U.S. patent application number 10/975668 was filed with the patent office on 2005-04-28 for direct type backlight unit having liftable frame structure.
This patent application is currently assigned to HANNSTAR DISPLAY CORP.. Invention is credited to Chen, Chin Jing, Huang, Hsin Fu.
Application Number | 20050088839 10/975668 |
Document ID | / |
Family ID | 34527640 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050088839 |
Kind Code |
A1 |
Huang, Hsin Fu ; et
al. |
April 28, 2005 |
Direct type backlight unit having liftable frame structure
Abstract
A direct type backlight unit having liftable frame structure
comprises a housing, an upper frame and a plurality of lamps,
wherein the plurality of lamps disposed on a cavity defined by the
housing and at least one has a foggy region; the upper frame is
configured to accommodate a plurality of optical films and a liquid
crystal panel and has two clip members for engaging with two
connection hole of the housing such that the upper frame can be
easily fixed on the housing. A plurality of lamp connection units
are disposed within the cavity and each comprises a conductive
clamp member for clamping the conductive electrode of the lamp,
thereby facilitating the replacement of the lamps.
Inventors: |
Huang, Hsin Fu; (Coahsiung,
TW) ; Chen, Chin Jing; (Coahsiung, TW) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Assignee: |
HANNSTAR DISPLAY CORP.
Taipei
TW
|
Family ID: |
34527640 |
Appl. No.: |
10/975668 |
Filed: |
October 29, 2004 |
Current U.S.
Class: |
362/633 |
Current CPC
Class: |
G02F 1/133604 20130101;
H01J 61/34 20130101; H01J 61/35 20130101 |
Class at
Publication: |
362/031 |
International
Class: |
F21V 007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2003 |
TW |
092130637 |
Sep 1, 2004 |
TW |
093100504 |
Sep 1, 2004 |
TW |
093100505 |
Claims
What is claimed is:
1. A direct type backlight unit having a liftable frame structure
comprising: a housing defining a cavity and having at least two
first connection elements; at least one lamp being disposed within
the cavity and having a conductive electrode for being connected to
a external power; and an upper frame defining a recess for
accommodating at least one optical film and defining an opening at
its bottom for receiving light provided by the lamp, and the upper
frame having at least two second connection elements respectively
connected with the first connection elements of the housing such
that the upper frame is fixed on the housing, wherein the first
connection elements are formed integrally with the housing and the
second connection elements are formed integrally with the upper
frame.
2. The direct type backlight unit having a liftable frame structure
as claimed in claim 1, wherein one of the first and second
connection elements are connection holes and the other are clip
members for engaging with the connection holes.
3. The direct type backlight unit having a liftable frame structure
as claimed in claim 1, further comprising a lamp connection unit
disposed within the cavity wherein the lamp connection unit has a
conductive clamp member which clamps the conductive electrode for
fixing the lamp within the cavity of the housing.
4. The direct type backlight unit having a liftable frame structure
as claimed in claim 3, wherein the conductive clamp member is
electrically connected to the external power.
5. The direct type backlight unit having a liftable frame structure
as claimed in claim 1, wherein the housing and the upper frame
further comprise at least one positioning hole and at least one
positioning element corresponding to the positioning hole in
position wherein the positioning hole is connected with the
positioning element such that the upper frame is positioned on the
housing.
6. The direct type backlight unit having a liftable frame structure
as claimed in claim 1, wherein the lamp has a foggy region formed
thereon.
7. The direct type backlight unit having a liftable frame structure
as claimed in claim 6, wherein the lamp includes a glass tube, and
the foggy region is formed by attaching a film to an outer surface
of the glass tube.
8. A liquid crystal display device comprising: a liquid crystal
panel having a display area; a direct type backlight unit disposed
below the liquid crystal panel, the direct type backlight unit
comprising: a housing defining a cavity; at least one lamp being
disposed within the cavity and having a conductive electrode for
being connected to a power; and an upper frame defining a recess
which accommodates the liquid crystal panel and defines an first
opening at its bottom for receiving light provided by the lamp, and
the upper frame having at least two first connection elements; and
an outer frame disposed upon the upper frame such that the liquid
crystal panel is fixed within the recess of the upper frame, and
the outer frame defining a second opening such that the display
area of the liquid crystal panel is exposed from the second
opening, wherein the outer frame has at least two second connection
elements respectively connected with the first connection elements
of the upper frame such that the outer frame is fixed on the upper
frame, wherein the first connection elements are formed integrally
with the upper frame and the second connection elements are formed
integrally with the outer frame.
9. The liquid crystal display device as claimed in claim 8, wherein
one of the first and second connection elements are connection
holes and the other are clip members for engaging with the
connection holes.
10. The liquid crystal display device as claimed in claim 9,
further comprising third connection elements formed integrally with
the housing and fourth connection elements formed integrally with
the upper frame wherein the upper frame is fixed on the housing by
connections of the third connection elements with the fourth
connection elements.
11. The liquid crystal display device as claimed in claim 8,
wherein the housing and the upper frame further comprise at least
one positioning hole and at least one positioning element
corresponding to the positioning hole in position wherein the
positioning hole is connected with the positioning element such
that the upper frame is positioned on the housing.
12. The liquid crystal display device as claimed in claim 8,
wherein the lamp has a foggy region formed thereon.
13. The liquid crystal display device as claimed in claim 8,
further comprising a lamp connection unit disposed within the
cavity, wherein the lamp connection unit has a conductive clamp
member which clamps the conductive electrode for fixing the lamp
within the cavity of the housing.
14. A backlight unit for illuminating a liquid crystal panel, the
backlight unit comprising: a housing having a base surface; a
reflector disposed on the base surface of the housing; and at least
one lamp being disposed within the housing and having a foggy
region formed thereon.
15. The backlight unit as claimed in claim 14, wherein the foggy
region is disposed on a surface of the lamp facing to the liquid
crystal panel.
16. The backlight unit as claimed in claim 14, wherein the housing
further has a top surface, and the backlight unit further comprises
a plurality of optical sheets disposed upon the top surface of the
housing.
17. The backlight unit as claimed in claim 14, wherein the foggy
region of the lamp is formed by a notching process.
18. The backlight unit as claimed in claim 14, wherein the foggy
region of the lamp is formed by a roughing process.
19. The backlight unit as claimed in claim 14, wherein the lamp
includes a glass tube, and the foggy region is formed by attaching
a film to an outer surface of the glass tube.
20. The backlight unit as claimed in claim 19, wherein the material
of the film is selected from the group consisting of polycarbonate
resin and poly-ethylene terephthalate resin.
21. The backlight unit as claimed in claim 19, wherein the film
further includes a scattering material with high optical
transparency.
22. The backlight unit as claimed in claim 21, wherein the
scattering material with high optical transparency is fine glass
power.
23. The backlight unit as claimed in claim 14, wherein the lamp
includes: a light-permeable tube defining a cavity; and an inner
light source disposed within the cavity of the light-permeable tube
for providing light to the liquid crystal panel.
24. The backlight unit as claimed in claim 23, wherein the foggy
region is formed by attaching a film to a surface of the
light-permeable tube.
25. The backlight unit as claimed in claim 23, wherein the
light-permeable tube has a reflecting film, and the reflecting film
is disposed on a surface of the light-permeable tube opposite to
the liquid crystal panel.
26. The backlight unit as claimed in claim 23, wherein the
light-permeable tube has at least one opening defined thereon.
27. The backlight unit as claimed in claim 23, wherein the lamp
further includes an external conductive electrode connected to the
light-permeable tube, and the external conductive electrode is
electrically connected to the inner light source and used to fix
the inner light source within the cavity of the light-permeable
tube.
28. The backlight unit as claimed in claim 27, further comprises a
lamp connection unit disposed upon the base surface of the housing,
and the lamp connection unit has a conductive clamp member for
clamping the external conductive electrode.
29. The backlight unit as claimed in claim 28, wherein the
conductive clamp member is electrically connected to an external
power.
30. A backlight unit for illuminating a liquid crystal panel, the
backlight unit comprising: a housing having a base surface; at
least one lamp having two conductive electrodes electrically
connected to an external power; and at least two lamp connection
units being disposed upon the base surface of the housing and each
having a conductive clamp member for clamping each external
conductive electrode of the lamp.
31. The backlight unit as claimed in claim 30, wherein the two
conductive electrodes are electrically connected to the external
power through the conductive clamp members of the lamp connection
units.
Description
[0001] This application claims the priority benefit of Taiwan
Patent Application Serial Number 092130637 filed Nov. 3, 2003,
Taiwan Patent Application Serial Number 093100504 filed Jan. 9,
2004 and Taiwan Patent Application Serial Number 093100505 filed
Jan. 9, 2004, the full disclosures of which are incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention generally relates to a direct type backlight
unit, and more particularly to a direct type backlight unit having
a liftable frame structure.
[0004] 2. Description of the Related Art
[0005] In general, a liquid crystal display typically has a
backlight unit for providing light needed by its liquid crystal
panel. However, the liquid crystal display may use different kinds
of backlight units depending on its use and size. The backlight
units mainly include two types, i.e. an edge type and a direct
type.
[0006] Due to the advantages of high luminance, high light
efficiency and simple structure, the direct type backlight unit is
widely used in large-size liquid crystal display devices.
[0007] FIG. 1 shows an exploded view of a conventional liquid
crystal display device 100. The liquid crystal display device 100
comprises a backlight unit 102, a set of optical films 104, a
liquid crystal panel 106 and an outer frame 108. The backlight unit
102 is disposed under the liquid crystal panel 106 for distributing
the light from a light source uniformly over the surface of the
liquid crystal panel 106. The backlight unit 102 comprises a
housing 103, a reflector 107 disposed upon the base surface of the
housing 103, and lamps 110, such as cold cathode fluorescent lamps
(CCFL), disposed within the housing 103. The set of optical films
104 is disposed between the backlight unit 102 and the liquid
crystal panel 106, and includes a diffuser 104a disposed upon the
backlight unit 102 and a plurality of optical sheets, such as a
prism sheet 140b and a diffusing sheet 140c, disposed on the
diffuser 104a. The outer frame 108 is disposed upon the liquid
crystal panel 106 and the set of optical films 104 and connected to
the backlight unit 102 so as to fix the liquid crystal panel 106
and the set of optical films 104 on the backlight unit 102, the
outer frame 108 is fixed to the housing 103 by the screws. FIG. 2
shows a cross-sectional view of the assembled liquid crystal
display 100 taken along line A-A in FIG. 1.
[0008] The lamps 110 are separately disposed within the cavity 105
formed by the housing 103 and positioned under the display area of
the liquid crystal panel 106 so as to distribute the light
uniformly over the surface of the liquid crystal panel 106. Each
lamp 110 has two terminals 110a and 110b, and each terminal has a
conductive end extending from the internal electrode of the lamp
110 and is connected to a conductive line 112 by a solder 114
formed by soldering as shown in FIG. 3; wherein the conductive line
112 is electrically connected to a power (not shown) so as to light
up each lamp 110.
[0009] However, in the structure of the conventional liquid crystal
display device 100, when the lamps are required to be repaired or
replaced, the outer frame 108 should be first removed and then
followed by the removal of the liquid crystal panel 106, the
plurality of optical sheets 104c, 104d and the diffuser 104a from
the backlight unit 102. Therefore, these removal steps might cause
a difficulty in disassembling or assembling work.
[0010] In prior art, a backlight unit having a middle frame
structure is provided for solving the above problem, which can be
found, for example, in U.S. Pat. No. 5,432,626 issued to Sasuga et
al. on Jul. 11, 1995, which is incorporated herein by reference. It
discloses a liquid crystal display device having an outer frame, a
middle frame and a lower frame wherein the middle frame is used for
supporting a diffuser and a liquid crystal panel and fixed on the
lower frame by a plurality of screws. Also, the outer frame has a
plurality of fasteners for respectively connecting the middle frame
and the lower frame. However, the connection structure of the
liquid crystal display device disclosed by Sasuga et al. is
accomplished by the plurality of screws and fasteners, which is
also inconvenient for disassembling or assembling work.
[0011] Further, in prior art (including Sasuga et al. patent), the
lamps 110 are electrically connected to a power by soldering as
shown in FIG. 3. Therefore, the solder 114 is required to be
removed before the lamp 110 will be taken out for repair or
replacement work. Furthermore, the soldering manner has tedious
processing steps and lower reliability. Also, if a defective solder
is formed by a bad soldering process, the solder connecting the
conductive end and the conductive line may be melted by a high
temperature generated while the lamps are lit up and therefore
results in short circuit. In addition, if a solder connecting the
conductive end and the conductive line is not well isolated, it may
generate point discharge and thus causes scorch or leakage
problems.
[0012] Additionally, in prior art, the backlight unit needs to be
reduced in thickness in order to make a thinner liquid crystal
display device. However, if the distance between the liquid crystal
panel and the lamps is too close, there will exist uneven luminance
problem, i.e., bright lines and dark lines presented on the liquid
crystal panel. Also, if the distance between the liquid crystal
panel and the lamps is increased, the whole thickness of the liquid
crystal display device will become larger. Further, if the distance
between the liquid crystal panel and the lamps is too far, the
luminance of the liquid crystal panel might be decreased to result
in inefficient light utilization. Accordingly, the present
invention provides a direct type backlight unit having a liftable
frame structure so as to facilitate the assembling and
disassembling works while replacing or repairing the lamps.
Further, the present invention can reduce the backlight unit in
thickness and avoid the uneven luminance problem at the same
time.
SUMMARY OF THE INVENTION
[0013] It is an object of the present invention to provide a direct
type backlight unit having a liftable frame structure so as to
facilitate the assembling and disassembling works while replacing
or repairing the lamps.
[0014] It is another object of the present invention to provide a
LCD backlight unit, which has a plurality of lamps wherein at least
one lamp has a foggy surface so as to reduce the backlight unit in
thickness and avoid the uneven luminance problem presented on the
liquid crystal panel.
[0015] In order to achieve the above objects, the present invention
provides a direct type backlight unit having a liftable frame
structure. The present direct type backlight unit comprises a
housing, a reflector, a upper frame and a plurality of lamps. The
reflector is disposed on the base surface of the housing. The
plurality of lamps are disposed within a cavity defined by the
housing and at least one lamp has a foggy region. The upper frame
is configured to accommodate a plurality of optical films and a
liquid crystal panel and has two clip members for engaging with two
connection hole of the housing. Further, the upper frame is
provided with a plurality of positioning elements and the housing
is provided with a plurality of positioning holes such that the
upper frame can be fixedly and accurately positioned on the housing
by the connection of the positioning elements and the positioning
holes. In addition, the direct type backlight unit having a
liftable frame structure comprises a plurality of lamp connection
unit wherein each lamp connection unit comprises a conductive clamp
member for clamping the conductive electrode of the lamp, thereby
facilitating the assembling and disassembling works while replacing
or repairing the lamps.
[0016] According to the direct type backlight unit of the present
invention, the upper frame is fixed on the housing by the clip
members and thus can be easily disassembled from the housing
without using any tools while the lamps will be repaired or
replaced. Also, since the plurality of optical films and the liquid
crystal panel are accommodated within the upper frame, they can be
removed together with the upper frame while the upper frame is
disassembled from the housing. In this manner, the plurality of
optical films and the liquid crystal panel will not be separated
and polluted so as to facilitate the assembling and disassembling
works while replacing or repairing the lamps.
[0017] In addition, according to the direct type backlight unit of
the present invention, each lamp connection unit has a clamp member
which is electrically connected to a power and electrically clamps
the conductive electrode of the lamp so as to light up each lamp.
In this configuration, the lamp can be electrically connected to a
power without using conventional soldering process. Also, the lamp
can be easily replaced without using any auxiliary tools.
[0018] Further, since the lamp of the backlight unit according to
the present invention has the foggy region, the distance between
the liquid crystal panel and the lamp can be reduced without
causing bright lines and dark lines on the liquid crystal panel,
i.e. without causing the uneven luminance problem. Therefore, the
backlight unit according to the present invention can be reduced so
as to make the liquid crystal display device thinner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Other objects, advantages, and novel features of the present
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings.
[0020] FIG. 1 is an exploded view of a conventional liquid crystal
display.
[0021] FIG. 2 is a cross-sectional view of the assembled liquid
crystal display taken along line A-A in FIG. 1.
[0022] FIG. 3 is an enlarged view of an electrical connection
between a conventional lamp and a conductive line.
[0023] FIG. 4 is an exploded view of a liquid crystal display
device according to one embodiment of the present invention.
[0024] FIG. 5 is a perspective view of the assembled liquid crystal
display (not including the outer frame) in FIG. 4.
[0025] FIG. 6 is a cross-sectional view of the assembled liquid
crystal display taken along line B-B in FIG. 5.
[0026] FIG. 7 is a schematic view of the assembled structure of the
outer frame and the backlight unit according to one embodiment of
the present invention.
[0027] FIG. 8 is a cross-sectional view of a backlight unit
according to other embodiment of the present invention.
[0028] FIG. 9a is an enlarged view of region A of the backlight
unit shown in FIG. 8.
[0029] FIG. 9b is a perspective view of region A of the backlight
unit shown in FIG. 8.
[0030] FIG. 10 is a cross-sectional view of a liquid crystal and a
backlight unit according to the present invention.
[0031] FIG. 11 is a top view of a liquid crystal and a backlight
unit according to the present invention.
[0032] FIG. 12 is a graph for showing the luminance data obtained
in first, second and third experiments.
[0033] FIG. 13 is a schematic view of the configuration of a lamp
according to one embodiment of the present invention.
[0034] FIG. 14 is a schematic view of the configuration of a lamp
according to another embodiment of the present invention.
[0035] FIGS. 15a and 15b illustrate two different manners for
fixing the inner light source within the light-permeable tube.
[0036] FIG. 16 is a perspective view of a lamp according to another
embodiment of the present invention.
[0037] FIG. 17 is a cross-sectional view taken along with line A-A
in FIG. 16.
[0038] FIG. 18 is a cross-sectional view of a lamp according to
another embodiment of the present invention.
[0039] FIG. 19 is a perspective view of a lamp according to another
embodiment of the present invention.
[0040] FIG. 20 is a schematic view of the configuration of a lamp
according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] FIG. 4 is an exploded view of a liquid crystal display
device 200 according to one embodiment of the present invention.
The liquid crystal display device 200 comprises a direct type
backlight unit 202, a set of optical films 204, a liquid crystal
panel 206 and an outer frame 208. The liquid crystal panel 206 is
used for producing an image and the direct type backlight unit 202
is used for emitting light to the liquid crystal panel 206. The set
of optical films 204 is disposed between the backlight unit 202 and
the liquid crystal panel 206. The set of optical films 204 includes
a diffuser 204a disposed upon the backlight unit 202 and a
plurality of optical sheets, such as a diffusing sheet 204b and a
prism sheet 204c, disposed on the diffuser 204a. The diffuser 204a
is disposed upon the backlight unit 202 and typically made of
half-transparent polyethylene terephthalate (PET), polyethylene
terephthalate (PC), or polycarbonate for further evenly diffusing
the light emitted from the backlight unit 202. Then, the diffused
light will pass through the plurality of optical sheet, such as the
diffusing sheet 204b and the prism sheet 204c, and finally reach
the liquid crystal panel 206. The outer frame 208 is disposed upon
the liquid crystal panel 206 and the set of optical films 204 so as
to fix the liquid crystal panel 206 and the set of optical films
204 upon the backlight unit 202. Further, the outer frame 208
defines an opening 208b thereof such that a display area 206a of
the liquid crystal panel 206 is exposed from the opening 208b of
the outer frame 208 after the outer frame 208 combines with the
backlight unit 202.
[0042] The backlight unit 202 comprises an upper frame 201 and a
housing 203, which defines a cavity 205 for accommodating a
plurality of lamps 210 such as cold cathode fluorescent lamps
(CCFL). The lamps 210 are separately disposed within the cavity 205
so as to provide the light to the liquid crystal panel 206. The
upper frame 201 has a recess 201 a for accommodating the set of
optical films 204 and the liquid crystal panel 206. The bottom of
the upper frame 201 further defines an opening 201b above the
cavity 205 of the housing 203 for receiving the light provided by
the lamps 210. The light provided by the lamps 210 can pass through
the opening 201b of the upper frame 201 to reach the set of optical
films 204, and then is uniformly distributed over the liquid
crystal panel 206 through the set of optical films 204.
[0043] The upper frame 201 has two clip members 207 respectively on
its two opposite outer side walls, and the housing 203 has two
connection hole 209 respectively on its two opposite outer side
walls. Preferably, the clip members 207 are formed integrally with
the upper frame 201, and the connection holes 209 are formed
integrally with the housing 203. The clip members 207 are
respectively positioned on the side walls 201c and downwardly
extend beyond the under surface 201d of the upper frame 201 wherein
their downward ends respectively form an inward hook 207a. While
the upper frame 201 is ready to combine with the housing 203, the
upper frame 201 is positioned above and aligned with the housing
203 and then downwardly pressed by an applied force such that the
inward hooks 207a can respectively contact the side walls 203a of
the housing 203 and downwardly move along the side walls 203a until
engaging with the connection holes 209. Therefore, the upper frame
201 can be easily fixed upon the housing 203 by the engagement of
the clip members 207 and the connection holes 209 as shown in FIG.
5 and FIG. 6.
[0044] Preferably, the upper frame 201 has a plurality of
positioning elements 211 on the periphery of the under surface
201d, and the housing 203 has a plurality of positioning holes 213
on the periphery surface 203b and respectively corresponding to the
positioning elements 211 in position. Therefore, the upper frame
201 can be fixedly and accurately positioned on the housing 203 by
the connection of the positioning elements 211 and the positioning
holes 213.
[0045] FIG. 5 and FIG. 6 are respectively a perspective view of the
assembled structure of the backlight unit 202, the set of optical
films 204 and the liquid crystal panel 206 (not including the outer
frame 208) in FIG. 4 and a cross-sectional view taken along line
B-B in FIG. 5. While the upper frame 201 is to be disassembled from
the housing 203, it can be easily separated from the housing 203 by
respectively and outwardly pulling the downward ends, i.e. the
position forming the inward hooks 207a, of the two clip members 207
and applying a upward force thereto.
[0046] According to one embodiment of the present invention, the
clip members 207 and/or the plurality of positioning elements 211
are disposed on the housing 203 and the connection holes 209 and/or
the plurality of positioning holes 213 are disposed on the upper
frame 201 (not shown), which can also achieve the objective of
facilitating the connection between the housing 203 and the upper
frame 201.
[0047] Further, according to the liquid crystal display device 200
of the present invention, the outer frame 208 can be connected to
the upper frame 201 of the backlight unit 202 by the
above-mentioned connection structure such that the liquid crystal
panel 206 and the set of optical films 204 can be secured within
the recess 201a by the outer frame 208.
[0048] FIG. 7 is a schematic view of the assembled structure of the
outer frame 208 and the backlight unit 202 according to one
embodiment of the present invention. The upper frame 201 has two
second connection holes 215 (only one shown) respectively on the
two opposite side walls 201e, and the outer frame 208 has two
second clip members 217 respectively on its two opposite side walls
208a. Preferably, the second clip members 217 are formed integrally
with the outer frame 208, and the second connection holes 215 are
formed integrally with the upper frame 201. The outer frame 208 is
fixed upon the upper frame 201 by the engagement of the second clip
members 217 and the second connection holes 215 such that the
disassembling and assembling works for the outer frame 208 and the
backlight unit 202 can become more easy.
[0049] FIG. 8 is a cross-sectional view of a backlight unit 320
according to other embodiment of the present invention. The
backlight unit 320 comprises a housing 370, a reflector 360
disposed on the base surface 374 of the housing 370, a plurality of
lamps 350 disposed within the housing 370 and a set of optical
films 340, such as a diffuser or a prism sheet, disposed upon the
top surface 372 of the housing 370 for providing uniform light to a
liquid crystal panel (not shown).
[0050] FIGS. 9a and 9b show the lamp 350 according to the present
invention. The lamp 350 is typically a cold cathode fluorescent
lamp (CCFL) or hot cathode fluorescent lamp (HCFL) having a thin
and long tube-like structure. The lamp 350 has a transparent
substance, such as a glass tube 354, and a mercury vapor 358 filled
inside. A fluorescent material (not shown) is applied over the
inner wall of the glass tube 354. When the lamp 350 is applied with
a voltage at its both terminals, the mercury vapor 358 will be
excited such that the fluorescent material can create visible
light.
[0051] The lamp 350 further has a foggy region 352 disposed on the
outer surface of the glass tube 354, i.e. on the outer surface
facing to the liquid crystal panel as shown in FIG. 8. The light
emitted by the lamp 350 will first pass through the foggy region
352 and be scattered by the foggy region 352, and then pass through
the set of optical films 340 to illuminate the liquid crystal panel
such that the lamp 350 can uniformly illuminate the liquid crystal
panel 313 without causing bright lines and dark lines on the liquid
crystal panel 313.
[0052] The foggy region 352 can be formed by various processes or
manners. For example, the foggy region 352 can be formed by
attaching a film to the glass tube 354 through a coating process, a
sticking process or a printing process. Alternatively, the foggy
region 352, for example, can be formed on the glass tube 354 by a
notching process or a roughing process such that a partial surface
of the glass tube 354 can become foggy and thus form the foggy
region 352.
[0053] For example, in a specific embodiment, the formation of the
foggy region 352 is achieved by a coating process to form a film on
the glass tube 354. The material of the film can be polycarbonate
(PC) resin or poly-ethylene terephthalate (PET) resin, and a
diffusant such as fine glass power or other scattering material
with high optical transparency is mixed or blended into the film.
It could be understood by the skilled in the art that the surface
area and thickness of the foggy region 352 of the lamp 350 will be
decided depending on the structure of the backlight unit 320, such
as the distance between the lamp 350 and the set of optical films
340 or the thickness of the backlight unit 320, etc.
[0054] Since the lamp 350 of the backlight unit 320 according to
the present invention has the foggy region 352, the distance
between the liquid crystal panel and the lamp 350 can be reduced
without causing bright lines and dark lines on the liquid crystal
panel, i.e. without causing the uneven luminance problem.
Therefore, the backlight unit according to the present invention
can be reduced so as to make the liquid crystal display device
thinner.
[0055] Referring to FIG. 10, it shows a liquid crystal panel 313
and a backlight unit 320 according to one specific embodiment of
the present invention. The backlight unit 320 comprises a plurality
of lamps 350 (eight in this embodiment) wherein the distance L
between two lamps 350 is about 23.5 mm, the diameter D of each lamp
350 is about 3 mm, and the distance H1 between the lamps 350 and
the reflector 360 is about 3.5 mm. An optical measuring equipment
380 such as luminance meter (Model: Topcon BM-7) is used to obtain
the luminance data of the backlight unit 320, wherein the distance
H3 between the optical measuring equipment 380 and the liquid
crystal panel 313 is about 50 cm.
[0056] Referring to FIG. 11, there are forty measurement points
(A1, A2, . . . , A39, A40) being selected along a central line,
i.e. dotted line A-A, of the liquid crystal panel 313. The distance
between the respective measurement points A1, A40 and the
respective side edge 382, 384 is about 124 mm, and the distance
between two adjacent measurement points is about 1 mm.
[0057] In the first experiment, the lamps 350 is not provided with
the foggy region, and the distance H2 between the reflector 360 and
the set of optical films 340 is about 15 mm, i.e. substantially
equal to the thickness of the backlight unit.
[0058] The luminance data are measured from the forty measurement
points (A1, A2, . . . , A39, A40) on the liquid crystal panel 313,
and the results are recorded in Table 1.
1TABLE 1 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 H2 (15 mm) 855.3 857.5
859.2 860.6 863 836.8 864.3 864.8 864.9 864.6 A11 A12 A13 A14 A15
A16 A17 A18 A19 A20 865.1 864.7 864.1 864.1 863.7 864 863.3 863.8
863.7 862.8 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 862.8 862.1
862.2 861.6 861.2 860.6 859.1 858.4 857.5 856.5 A31 A32 A33 A34 A35
A36 A37 A38 A39 A40 855.4 854.4 853.2 852.8 850.8 849.1 846.9 845.3
842.3 840.3 Standard Deviation Value: 7.44 Mean: 858.1
cd/m.sup.2
[0059] In the second experiment, the lamp 350 is not provided with
the foggy region, and the distance H2 between the reflector 360 and
the set of optical films 340 is about 12 mm, i.e. substantially
equal to the thickness of the backlight unit. The luminance data
are measured from the forty measurement points (A1, A2, . . . ,
A39, A40) on the liquid crystal panel 313, and the results are
recorded in Table 2.
2TABLE 2 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 H2 (12 mm) 956.3 958.7
960.4 962.9 964.2 965.4 966.3 967.3 967.8 968.2 A11 A12 A13 A14 A15
A16 A17 A18 A19 A20 968.3 967.2 965.8 964.7 963.1 960.5 958.3 956.7
955.5 954.1 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 953.2 953.3
952.8 953.4 952.9 953.2 953.2 952.8 952.5 952.2 A31 A32 A33 A34 A35
A36 A37 A38 A39 A40 951.4 949.8 948.8 947.6 946.6 946 944.8 943.5
941.6 939.9 Standard Deviation Value: 8.00 Mean 956.0
cd/m.sup.2
[0060] In the third experiment, the lamp 350 is provided with a
foggy region 352 thereon, and the distance H2 between the reflector
360 and the set of optical films 340 is still about 12 mm, i.e.
substantially equal to the thickness of the backlight unit. The
foggy region 352 is formed by attaching a diffusing sheet to the
surface of the lamp 350. In this experiment, the diffusing sheet is
the product D121Z commercially obtained from Tsujiden Co., Ltd. The
diffusing sheet is about 2 mm in width, and its material is
poly-ethylene terephthalate (PET). The luminance data are measured
from the forty measurement points (A1, A2, . . . , A39, A40) on the
liquid crystal panel 313, and the results are recorded in Table
3.
3TABLE 3 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 H2 (12 mm) 943.1 945.5
948.2 950.3 951.8 952.7 954.4 955.8 956.3 957 A11 A12 A13 A14 A15
A16 A17 A18 A19 A20 957.1 956.8 955.8 955.6 953.9 953.3 952.7 950.4
948.9 948.1 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 947.2 946.7
946.6 946.8 947.2 947.3 947.2 946.4 946.3 946 A31 A32 A33 A34 A35
A36 A37 A38 A39 A40 945.5 944.5 944.1 942.8 941.4 940 938.9 937.7
935.9 933.4 Standard Deviation Value: 6.05 Mean 948.0
cd/m.sup.2
[0061] FIG. 12 is a graph for showing the luminance data in Table
1, Table 2 and Table 3. As shown in FIG. 12, the liquid crystal
panel of the third experiment, in which the lamp 350 has the foggy
region 352, has higher luminance than that of the first experiment.
Also, the difference between the highest luminance value and the
lowest luminance value in the third experiment is smaller than that
in the second experiment; therefore, the luminance range in the
third experiment is smaller than that in the second experiment.
[0062] Further, the second experiment and the third experiment can
be further discussed through the concept of standard deviation so
as to better understand the luminance uniformity. The standard
deviation is used to show the variability between the data and the
mean. That is, the variability is large if the standard deviation
is large, and the variability is small if the standard deviation is
small.
[0063] The standard deviations of the data in the second and third
experiment are respectively 8.00 and 6.05. Therefore, the
variability between the data and the mean in the third experiment
is smaller than that in the second experiment. That is, the
luminance of the liquid crystal panel in the third experiment is
more uniform than that in the second experiment. Further, after
comparison between the standard deviation value 6.05 of the third
experiment and the standard deviation value 7.44 of the first
experiment, it could be found that the luminance of the liquid
crystal panel in the third experiment is more uniform than that in
the first experiment.
[0064] In the first, second and third experiments, the manner of
using the optical measuring equipment to observe the luminance of
the liquid crystal panel can be alternatively replaced by the
manner of using a camera to take the pictures of the liquid crystal
panel 313 and indirectly observing the luminance changes through
the pictures, or the manner of directly observing the luminance
changes on the liquid crystal panel. For example, the picture of
the liquid crystal panel 313 taken in the first experiment does not
present bright lines and dark lines. The picture of the liquid
crystal panel 313 taken in the second experiment presents bright
lines and dark lines, which are alternatively presented one by one
on the crystal panel 313 and corresponding to the number of the
lamps. The picture of the liquid crystal panel 313 taken in the
third experiment does not present bright lines and dark lines.
[0065] As described above, the present invention can reduce the
backlight unit in thickness and avoid the uneven luminance problem
at the same time.
[0066] FIG. 13 is a schematic view of the configuration of the lamp
350 according to one embodiment of the present invention. Each lamp
350 has two terminals 350a and 350b, and each terminal has an
external conductive electrode 364 and 366 disposed thereon for
electrically connecting with a power (not shown) so as to light up
the lamps 350. FIG. 13 further shows two lamp connection units 368
and 369, which are disposed within a cavity 370a defined by the
housing 370 as shown in FIG. 10. The lamp connection units 368 and
369 respectively have a conductive clamp member 368a and 369a
electrically connected to a power (not shown). The conductive clamp
members 368a and 369a respectively clamp the external conductive
electrode 364 and 366 of each lamp 350 so as to fix the lamps 350
upon the base surface 374 of the housing 370. In addition, the
conductive clamp members 368a, 369a clamping the two terminals are
respectively connected to the positive electrode and the negative
electrode of the power so as to light up each lamp 350. According
to the lamp configuration of the present invention, a lamp can be
easily replaced and repaired without proceeding with tedious
soldering process.
[0067] It should be noted that the feature of the lamp connection
units 368 and 369 can be made in different shape in accordance with
different requirements so as to fit the different shape of external
conductive electrodes 364 and 366.
[0068] FIG. 14 is a schematic view of the configuration of a lamp
450 according to another embodiment of the present invention. The
lamp 450 includes an inner light source 461 and a light-permeable
tube 462. Preferably, the inner light source 461 is a cold cathode
fluorescent lamp (CCFL) or hot cathode fluorescent lamp (HCFL). The
inner light source 461 is fixedly disposed within a cavity 463,
which is defined by the light-permeable tube 462, through two
external conductive electrodes 464 and 466. The external conductive
electrodes 464 and 466 are respectively disposed at two openings
(not shown) of the light-permeable tube 462 for fixing two
terminals 461a and 461b of the inner light source 461. Further, the
two terminals 461a and 461b of the inner light source 461
respectively have an inner conductive electrode (not shown)
electrically connected to the respective external conductive
electrode 461a, 461b. FIGS. 15a and 15b illustrate two different
manners for fixing the inner light source 461 within the
light-permeable tube 462. In addition, two lamp connection units
468 and 469 and their conductive clamp members 468a and 469a units
shown in FIG. 14 are substantially the same with those shown in
FIG. 13.
[0069] Referring to FIG. 15a and FIG. 15b, the external conductive
electrodes 464 and 466 are designed as caps and respectively define
a connection hole 494 for respectively connecting with two openings
462a, 462b of the light-permeable tube 462. As shown in FIG. 15a,
the inner conductive electrodes 490 and 492 at the two terminals
461a and 461b of the inner light source 461 are lead types and can
be electrically and fixedly connected to the external conductive
electrodes 464 and 466 by soldering manner. In FIG. 15b, the inner
conductive electrodes 490 and 492 at the two terminals 461a and
461b of the inner light source 461 are preferably metal tape types,
which are respectively wrapped around the two terminals 461a and
461b of the inner light source 461; the two terminals 461a and 461b
can be respectively inserted into a insertion hole 496 formed
within the connection hole 494 so as to be electrically connected
and fixed to the external conductive electrodes 464 and 466.
[0070] FIG. 16 and FIG. 17 are respectively a perspective view and
a cross-sectional view of the lamp 450 taken along with line A-A in
FIG. 16 according to another embodiment of the present invention. A
foggy region 452 is disposed on the outer surface of the
light-permeable tube 462, i.e. on the outer surface facing to a
liquid crystal panel (not shown), which can also achieve the
objectives of reducing the thickness of the backlight unit and
avoiding the uneven luminance problem of the liquid crystal panel.
In addition, a reflecting film 498 can be disposed on the opposite
outer surface, opposite to the foggy region 452, of the
light-permeable tube 462, i.e. on the outer surface opposite to the
liquid crystal panel so as to improve the light utilization
efficiency of the lamps.
[0071] FIG. 18 is a cross-sectional view of the lamp according to
another embodiment of the present invention. The foggy region 452
is disposed on the inner surface of the light-permeable tube 462.
In addition, the reflecting film 498 is disposed on the opposite
inner surface, which is opposite to the foggy region 452.
[0072] In the above embodiments, the light-permeable tube 462
preferably has an opening 500, as shown in FIG. 19, for increasing
light transmittance and improving heat dissipation effect. Further,
the opening 500 can be disposed at any position on the
light-permeable tube 462 and therefore not limited to the
embodiment of the present invention.
[0073] It should be understood that the external conductive
electrodes 464, 466 and lamp connection units 468, 469 in the above
embodiments could also be designed to have some positioning
mechanisms such that the foggy region 452, the reflecting film 498
or the opening 500 of the light-permeable tube 462 can be well
positioned and effectively utilized. FIG. 20 is a schematic view of
the configuration of the lamp 450 according to anther embodiment of
the present invention. The external conductive electrodes 464 and
466 are designed as square, and each has two V-shaped notches 602
respectively formed on its two side walls 464a, 466a. In addition,
the conductive clamp members 468a and 469a of the lamp connection
units 468 and 469 respectively have two V-shaped protrusions 604
corresponding to the V-shaped notches 602 such that the external
conductive electrodes 464 and 466 can be respectively and fixedly
clamped within the lamp connection units 468 and 469.
[0074] In the above-mentioned embodiments, the light-permeable tube
462 is preferably made of transparent glass or any other
light-permeable materials.
[0075] The aspect of the present invention is that a backlight unit
comprises a housing for accommodating lamps and an upper frame for
accommodating a plurality of optical films and a liquid crystal
panel; wherein the upper frame and the housing can be secured to
each other by the engagement structure of the clip members and the
connection holes such that the plurality of optical films and the
liquid crystal panel can be easily removed while the upper frame is
disassembled from the housing, and further such that the assembling
and disassembling works while replacing or repairing the lamps can
be more easily accomplished. Further, the lamp of the backlight
unit according to present invention has the foggy region thereby
reducing the distance between the liquid crystal panel and the
lamps and avoiding the uneven luminance problem at the same time.
Also, each lamp is fixed within the cavity by the conductive clamp
member of the lamp connection unit and electrically connected to a
power such that the lamp can be replaced or repaired without a
tedious soldering process.
[0076] Although the invention has been explained in relation to its
preferred embodiment, it is not used to limit the invention. It is
to be understood that many other possible modifications and
variations can be made by those skilled in the art without
departing from the spirit and scope of the invention as hereinafter
claimed.
* * * * *